package gold.utils;

/**
 * Created by fanzhenyu02 on 2020/8/19.
 */
public class DijkstraUtil {

    static final int V = 9;

    public int[] dijkstra(int graph[][], int src) {
        int dist[] = new int[V];

        Boolean sptSet[] = new Boolean[V];

        for (int i = 0; i < V; i++) {
            dist[i] = Integer.MAX_VALUE;
            sptSet[i] = false;
        }
        dist[src] = 0;
        for (int count = 0; count < V - 1; count++) {
            int u = minDistance(dist, sptSet);
            sptSet[u] = true;
            for (int v = 0; v < V; v++) {
                if (!sptSet[v] && graph[u][v] != 0 &&
                        dist[u] != Integer.MAX_VALUE &&
                        dist[u] + graph[u][v] < dist[v]) {
                    dist[v] = dist[u] + graph[u][v];
                }
            }
        }

        return dist;
    }

    public int minDistance(int dist[], Boolean sptSet[]) {
        //  初始化最小值
        int min = Integer.MAX_VALUE, min_index = -1;
        for (int v = 0; v < V; v++)
            if (sptSet[v] == false && dist[v] <= min) {
                min = dist[v];
                min_index = v;
            }
        return min_index;
    }

    public static void printSolution(int dist[], int n) {
        System.out.println("Vertex            Distance from Source");
        for (int i = 0; i < V; i++)
            System.out.println(i + " from source: " + dist[i]);
    }

    public static void main(String[] args) {
        int graph[][] = new int[][]{
                {0, 4, 0, 0, 0, 0, 0, 8, 0},
                {4, 0, 8, 0, 0, 0, 0, 11, 0},
                {0, 8, 0, 7, 0, 4, 0, 0, 2},
                {0, 0, 7, 0, 9, 14, 0, 0, 0},
                {0, 0, 0, 9, 0, 10, 0, 0, 0},
                {0, 0, 4, 14, 10, 0, 2, 0, 0},
                {0, 0, 0, 0, 0, 2, 0, 1, 6},
                {8, 11, 0, 0, 0, 0, 1, 0, 7},
                {0, 0, 2, 0, 0, 0, 6, 7, 0}
        };

        DijkstraUtil t = new DijkstraUtil();
        int[] dist = t.dijkstra(graph, 0);
        printSolution(dist, V);
    }
}
